THE TERNS, SKIMMERS, AND GULLS 



2279 



Terns 



there are two notches on each side of the hinder margin of the breastbone; the 

 toes may be either partially or fully webbed, and the claws are feeble or of 

 moderate length. 



The terns, of which eleven genera are recognized by Mr. Saunders, 

 constftute a subfamily (Sternince} characterized by the straight and 

 rather slender beak, in which the two mandibles are of nearly equal length; by the 

 feather tracts resembling those of the plovers in their arrangement; and by the 

 slight or distinct forking of the tail. In Britain the group is represented by two 

 genera, and it is to these that our notice is mainly confined. The marsh terns form 

 a genus {Hydrochelidon) represented by four species, three of which are British. 

 Belonging to a group of genera, in which the tail may be either nearly square or 

 deeply forked, and the head devoid of elongated plumes at the gape of the mouth, 

 the marsh terns are specially distinguished by the rounded or slightly-pointed tail 

 feathers, the short tail, which is less than half the length of the wing, the small 

 beak, with the culmen less than twice the length of the metatarsus, and the feeble 

 feet, in which the webs are considerably indented between the toes. All these 

 terns nest in marshes, either on tussocks of grass, or among floating vegetation. 

 The best known of the British species is the black tern (ff. nigra), in which the 

 under parts in the adult summer plumage are dark leaden gray, the upper tail 

 coverts and tail being gray, the beak black, the chin and sides of the face like the 

 under parts, the crown nearly black, and the under wing coverts pale gray. On 

 the other hand, the whiskered tern {ff. hybrida), which is but an occasional 

 straggler to Britain from the south, has the beak blood red, the chin and sides of 

 the face pure white, the throat and breast gray, passing into blackish gray on the 

 abdomen, and 

 the under wing 

 coverts white. 

 Abundant in 

 Southern Eu- 

 rope, this tern 

 ranges over a 

 large part of 

 Africa and most 

 of Asia. The 

 beautiful white- 

 winged black 

 tern {ff. leucop- 



tera), which is likewise but a rare visitor to the British Isles, differs from both the 

 preceding in that the upper tail coverts and tail are white in the adult summer 

 plumage, the under parts being black as far as the vent, and the under wing coverts 

 of the same hue, while the beak is dull red. Rare in Northern Europe, this species 

 is more common in the south and east, whence its range extends over the greater 

 portion of Europe. Mr. Saunders writes that " the black tern breeds in colonies, 

 the nest being situated in marshes, and formed of decayed pieces of Equisetum and 

 other plants, or heaps of wrack, which rise and fall with the tide; sometimes they 



HEAD OF BROAD-BILLED TKRN. 

 (From Saunders, Proc. Zool. Soc., 1876.) 



